This invention relates to computer image generation (CIG), and, more particularly, to apparatus and methods for generating display data for a desired image presentation on a plurality of display devices, wherein the display data for each device is derived from a portion of conventional source data for a single display.
CIG may be employed to provide simulated visual representations useful for training, such as for an airplane pilot or tank driver, without having to operate the actual vehicle. In certain applications, an adequate overall visual image may be presented by a combination of a full high resolution display disposed about the line of sight of an observer with lower resolution images at the periphery, on the side or as background. Use of lower resolution displays, like those based on 525 line television standards (typically two interlaced fields of 262.5 lines each), generally produce a distracting raster prominence when displayed over an expanded area.
In a real time computer image generation system (see for example U.S. Pat. No. 4,727,365 to Bunker et al which is assigned to the instant assignee) display data for at least one and typically two full high resolution channels are generated. The term "full resolution" as used herein refers to having corresponding pixel modulation values for each pixel of a line and for all lines of the display. One presently employed high resolution display features 1,023 lines by 1,000 pixels per line per frame, conventionally referred to as a "1K by 1K" display. It should be understood that the present invention is applicable to any display regardless of the actual number of lines and actual number of pixels per line of the display.
For a typical CIG system, image generation can be regarded as occurring in sequentially coupled processing stages, conventionally designated as a controller, a geometry processor and a display processor. Very briefly, the controller receives inputs that indicate an operator's position and orientation; the geometry processor obtains scene descriptors from a data base and rotates and clips the resulting images in response to inputs from the controller: and, the display processor determines for the image to be displayed a color modulation value for each pixel of the display device to be used. A more detailed description of the operation of a computer image generator may be had by reference to the above-identified Bunker et al patent.
A typical display frame is formed from two interlaced fields that are raster scanned, such as in the U.S. television standard wherein a new field is supplied each 1/60 of a second so that a new frame is presented each 1/30 of a second. Determining the appropriate full pixel modulation values for a plurality of 1K by 1K display devices places a tremendous computing burden on the display processor, such that one display processor will typically supply image information for only one or two 1K by 1K display devices.
In certain applications, it may be desirable to have more than two displays. Since a full high resolution display may be only required around the line of sight, it would be desirable to take the image data generated for one 1K by 1K display device and apportion it among a plurality of 1K by 1K display devices while achieving adequate image quality for each of the plurality of display devices. Although some fine detail and overall resolution may be expected to be lost by such distribution of the image data, the resulting image displays, which may be used for background and/or off line-of-sight, or peripheral representations, may be considered acceptable. Further, the display processor is hardware intensive and appropriately distributing the image data among a plurality of displays could save the expense of having to replicate additional display processors to provide full high resolution image data to each of the plurality of displays.
In order to avoid the expense associated with adding hardware, including memory and processing apparatus, for generating display data for full high resolution, it would be desirable to use a respective portion of the full high resolution data available from a currently employed display processor to generate pixel modulation data for controlling displays on a respective plurality of high resolution devices, while avoiding raster prominence and achieving acceptable resolution.
Accordingly, it is an object of the present invention to provide a display system for a computer image generation system, wherein the CIG system produces data for one display system having a predetermined resolution and further wherein a pixel modulation manipulation system produces data for a plurality of displays having the predetermined resolution from the data for the one display.
Another object is to provide a method for deriving data for a high resolution display from a predetermined portion of data for a full high resolution display.
Still another object is to provide a method for deriving data for a plurality of high resolution displays from data for one full high resolution display.
Yet another object is to provide a method for deriving data for a plurality of displays having a predetermined resolution from data for one display having the predetermined resolution.